Biodiesel fuel mixtures

ABSTRACT

Provided herein are biodiesel fuel mixtures having improved properties for reducing NOx emissions as well as total particular matter emissions, CO emissions, and total hydrocarbon emissions.

BACKGROUND

Biodiesel, an alternative diesel fuel created from the esterification offats and fatty acids, continues to gain significant interest as arenewable energy source. The biodiesel market is expected to reach 6,453million liters in the U.S. by 2020 and 45,291 million liters globally.See GlobalData, Global Biodiesel Market Analysis and Forecasts to 2020,Accessed May 26, 2012 and Fuel Processing Technology 106 (2013) 526-532.Biodiesel is an attractive alternative fuel source worldwide because itoperates in conventional engines, does not require special storage, hasless odor offensive exhaust, and has a higher flash point, therebymaking it a safer energy source than conventional diesel fuel.

Despite these advantages, a major impediment to the wide-spreadcommitted use of biodiesel has been the observed increase in NO_(x)emissions. For example, for 100% biodiesel, NO_(x) emissions canincrease by 13% or more. See Ener Conver and Manag, 50, (2009), 14-34.Excessive NOx emission causes smog, ground level ozone, and acid rain.See Journal of Scientific & Industrial Industry Research, Vol. 73, March2014, 177-180. This is a significant drawback, particularly sincegovernmental agencies continue to impose new legislation on “cleanerair” and mandate higher emission standards for motor vehicles. Thus, arising concern is that biodiesel may not be able to meet theseheightened requirements.

The need therefore remains for biodiesel fuels which do not negativelyimpact NO_(x) emission, as well as other criteria pollutants such asparticulate matter, total hydrocarbons and carbon monoxide.

SUMMARY

Provided herein are biodiesel fuel mixtures comprising a first biodieselfuel, a second biodiesel fuel, a base petroleum diesel fuel, and anadditive. The disclosed biodiesel fuel mixtures comprise a cetane numberof 45 to 70 and have no negative impact on NO_(x) emissions. Indeed, thedisclosed mixtures decrease NO_(x) emission by 1 to 7%. See e.g., Table12. The disclosed mixtures also decrease total particular matteremissions, CO emissions, and total hydrocarbon emissions. See e.g.,Table 12.

Process for manufacturing the disclosed biodiesel fuel mixtures are alsoprovided.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graphic representation of torque and speed commands for thetransient cycle for heavy-duty engines.

FIG. 2 is a schematic of sampling system used for transient emissionmeasurements.

FIG. 3 shows the engine performance maps for screening tests.

FIG. 4 shows the engine performance maps for screening tests at 3000 ppmadditive.

FIG. 5 shows the engine performance maps for screening tests at 2000 ppmadditive.

FIG. 6 illustrates additive concentration vs. NO_(x) results.

FIG. 7 shows a comparison of B20 blends.

FIG. 8 shows a comparison of B20 blends with 3000 ppm A1

FIG. 9 shows a comparison of B20 blends with 3000 ppm additive.

DETAILED DESCRIPTION

In a first embodiment, provided herein are biodiesel fuel mixturescomprising a first biodiesel fuel, a second biodiesel fuel, a basepetroleum diesel fuel, and an additive, wherein the biodiesel fuelmixture has a cetane number of 45 to 70.

In a second embodiment, provided herein are biodiesel fuel mixturescomprising 12-15 wt. % of a first biodiesel fuel, 6-8 wt. % of a secondbiodiesel fuel, 79-81 wt. % of a base petroleum diesel fuel, and anadditive, wherein the biodiesel fuel mixture has a cetane number of 45to 70.

In a third embodiment, provided herein are biodiesel fuel mixturescomprising 13 wt. % of a first biodiesel fuel, 7 wt. % of a secondbiodiesel fuel, 80 wt. % of a base petroleum diesel fuel, and from 100to 3500 ppm of an additive, wherein the biodiesel fuel mixture has acetane number of 45 to 70.

1. Definitions

The term “biodiesel” means a fuel derived from vegetable oils or animalfats. Biodiesel includes fuels comprising mono-alkyl esters oflong-chain fatty acids derived from the transesterification of fatsobtained from vegetable oils or other fatty acids such as animal fats orwaste cooking oils as well as fuel resulting from hydrotreatingvegetable oils, animal fats or mono-alkyl esters of long-chain fattyacids. In one aspect, the biodiesel used herein comprises fatty acidmethyl esters (FAMEs) derived from the transesterification of vegetableoil with methanol.

“Petroleum diesel fuel” and “base petroleum diesel fuel” are usedinterchangeably and refer to a combustible petroleum distillate used asfuel for diesel engines. Petroleum diesel fuel is typically formed fromthe fractional distillation of crude oil between 200° C. and 350° C. atatmospheric pressure, resulting in a mixture of carbon chains comprisingbetween 8 and 21 carbon atoms per molecule.

The term “no negative impact” as in, wherein the mixture has no negativeimpact on NO_(x) emissions, means that there is no statisticallysignificant increase in the amount of NO_(x) emission using thedisclosed biodiesel fuel mixture when compared to petroleum diesel fuelin the same engine. Statistical significance is based from the knownone-sided Student's t-statistics as set for in Snedecor and Cochran,Statistical Methods (7^(th) edition). Pg 91, Iowa State UniversityPress, 1980, e.g., a cut-off value of 0.5 or less.

2. Fuel Mixtures

In a fourth embodiment, the biodiesel fuel mixtures described hereinhave a cetane number of 45 to 65, wherein the remaining features are asdescribed above in the first, second, or third embodiment.Alternatively, the biodiesel fuel mixtures described herein have acetane number of 45 to 60, 45 to 55, 55 to 65, 50 to 60, 48 to 51, or 58to 60, wherein the remaining features are as described above in thefirst, second, or third embodiment.

In a fifth embodiment, the biodiesel fuel mixtures described hereincomprise 25% or less of aromatics by volume, wherein the remainingfeatures are as described above in the first, second, third, or fourthembodiment. Alternatively, the biodiesel fuel mixture described hereincomprise 20% or less of aromatics by volume, 15% or less of aromatics byvolume, 12% or less of aromatics by volume, 10% or less of aromatics byvolume, or 20% to 25% aromatics by volume, wherein the remainingfeatures are as described above in the first, second, third, or fourthembodiment.

In a sixth embodiment, the biodiesel fuel mixtures described hereincomprise less than 7% polycyclic aromatics by weight, wherein theremaining features are as described above in the first, second, third,fourth, or fifth embodiment. Alternatively, the biodiesel fuel mixturesdescribed herein comprise less than 5% polycyclic aromatics by weight or4.5% to 5.5% polycyclic aromatics by weight, wherein the remainingfeatures are as described above in the first, second, third, fourth, orfifth embodiment.

In a seventh embodiment, the weight ratio of total aromatics topolycyclic aromatics in the biodiesel fuel mixtures described herein is5:1, wherein the remaining features are as described above in the first,second, third, fourth, fifth, or sixth embodiment. Alternatively, theweight ratio of total aromatics to polycyclic aromatics in the biodieselfuel mixtures described herein is 4:1, 3:1, or 2:1, wherein theremaining features are as described above in the first, second, third,fourth, fifth, or sixth embodiment.

In an eighth embodiment, the sulfur content in the biodiesel fuelmixtures described herein is less than 15 ppm, wherein the remainingfeatures are as described above in the first, second, third, fourth,fifth, sixth, or seventh embodiment. Alternatively, the sulfur contentin the biodiesel fuel mixtures described herein is less than 10 ppm,less than 5 ppm, less than 1.0 ppm, wherein the remaining features areas described above in the first, second, third, fourth, fifth, sixth, orseventh embodiment.

In a ninth embodiment, the nitrogen content in the biodiesel fuelmixtures described herein is from 0 to about 800 ppm, wherein theremaining features are as described above in the first, second, third,fourth, fifth, sixth, seventh, or eighth embodiment. 200 ppm or higher,wherein the remaining features are as described above in the first,second, third, fourth, fifth, sixth, seventh, or eighth embodiment.Alternatively, the nitrogen content in the biodiesel fuel mixturesdescribed herein is from 50 ppm to about 600 ppm, from about 100 toabout 400 ppm, from about 200 to about 800 ppm, from about 10 to about600 ppm, and from about 250 to about 300 ppm, wherein the remainingfeatures are as described above in the first, second, third, fourth,fifth, sixth, seventh, or eighth embodiment.

In a tenth embodiment, the fatty acid methyl ester content in thebiodiesel fuel mixtures described herein is 15 to 25% or 19 to 21%,wherein the remaining features are as described above in the first,second, third, fourth, fifth, sixth, seventh, eighth, or ninthembodiment.

In an eleventh embodiment, the viscosity at 40° C. in the biodiesel fuelmixtures described herein is 1.9 to 4.1 centistokes, wherein theremaining features are as described above in the first, second, third,fourth, fifth, sixth, seventh, eighth, ninth, or tenth embodiment.

In a twelfth embodiment, the additive in the biodiesel fuel mixturesdescribed herein is present in an amount of 500, 1000, 1500, 2000, 2500,3000, 3300, 4000, 5000, 6000, 7000, 8000, 9000 or 10,000 ppm, whereinthe remaining features are as described above in the first, second,third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, or eleventhembodiment. Alternatively, the additive is present in an amount of 3300ppm or 3000 ppm, wherein the remaining features are as described abovein the first, second, third, fourth, fifth, sixth, seventh, eighth,ninth, tenth, or eleventh embodiment.

In a thirteenth embodiment, the additive in the biodiesel fuel mixturesdescribed herein is selected from an amine-based antioxidant, aphenol-based antioxidant, or a nitrated alkyl-based antioxidant, whereinthe remaining features are as described above in the first, second,third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, ortwelfth embodiment. Alternatively, the additive is selected from2-ethylhexyl nitrate (2-EHN); di-tert-butyl peroxide (DTBP); tertiarybutylhydroquinone (TBHQ); N,N-di-sec-butyl-1,4-phenylenediamine (DTBP),N,N′-diphenyl-1,4-phenylenediamine (DPPD); andN-phenyl-1,4-phenylenediamine (NPPD), wherein the remaining features areas described above in the first, second, third, fourth, fifth, sixth,seventh, eighth, ninth, tenth, eleventh, or twelfth embodiment. Inanother alternative, the additive is 2-ethylhexyl nitrate, wherein theremaining features are as described above in the first, second, third,fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, ortwelfth embodiment.

In a fourteenth embodiment, the biodiesel fuel mixtures described hereinhave no negative impact on NO_(x) emissions, wherein the remainingfeatures are as described above in the first, second, third, fourth,fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, orthirteenth embodiment.

In a fifteenth embodiment, the biodiesel fuel mixtures described hereindecrease NO_(x) emissions of an engine by 1 to 7%, wherein the remainingfeatures are as described above in the first, second, third, fourth,fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth,thirteenth, or fourteenth embodiment. Alternatively, the biodiesel fuelmixtures described herein decrease NO_(x) emissions of an engine by 2 to7%; by 3 to 7%; or by 5 to 7%, wherein the remaining features are asdescribed above in the first, second, third, fourth, fifth, sixth,seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, orfourteenth embodiment. In one alternative, the biodiesel fuel mixturesdescribed herein comprise NOx emissions equivalent to those of areference fuel having the following specifications: sulfur (15 ppmmaximum), aromatics (10 vol % maximum), polycyclic aromatics (10 wt %maximum), nitrogen (10 ppm maximum), unadditized cetane number (48minimum), API gravity (33-39), flash point (130° F. minimum), viscosity@ 40° C., cSt (2.0-4.12), IBP (340 to 420° F.), 10% (400 to 490° F.),50% (470 to 560° F.), 90% (550 to 610° F.), and EP (580 to 660° F.).

In a sixteenth embodiment, the biodiesel fuel mixtures described hereindecrease total particular matter emissions of an engine by 20 to 25%,wherein the remaining features are as described above in the first,second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth,eleventh, twelfth, thirteenth, fourteenth, or fifteenth embodiment.

In a seventeenth embodiment, the biodiesel fuel mixtures describedherein decrease CO emissions of an engine by 15 to 25%, wherein theremaining features are as described above in the first, second, third,fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth,thirteenth, fourteenth, fifteenth, or sixteenth embodiment.

In an eighteenth embodiment, the biodiesel fuel mixtures describedherein decrease total hydrocarbon emissions of an engine by 15 to 25%,wherein the remaining features are as described above in the first,second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth,eleventh, twelfth, thirteenth, fourteenth, fifteenth, sixteenth, orseventeenth embodiment.

In a nineteenth embodiment, the engine used to test the properties ofthe biodiesel fuel mixtures described herein is a diesel engine such asa Detroit Diesel Corporation Series 60 heavy duty diesel engine or aCummins ISM 370 diesel engine.

In a twentieth embodiment, the biodiesel fuel mixtures, and accompanyingproperties and features are as described below in the exemplificationsection.

EXEMPLIFICATION

The following starting fuels and additives were blended at variousconcentrations. Table 1 provides codes for the six additives and Table 2lists the fuel codes corresponding to each fuel blend and theconcentrations.

TABLE 1 Component % Additive Code 2-EHN DTBP PDA A1, A7 100 0 0 A2 91 09 A3 91 9 0 A4 0 100 0 A5 82 9 9 A6 0 0 100

TABLE 2 Concentration, %^(a) Fuel Base Code Fuel Biodiesel 1 Biodiesel 2Biodiesel 3 Additive/Conc. F1 — 100  — — — F2 — — 100  — — F3 — — — 100 — F4 100  — — — — F5 80 13 7 — — F6 80 — — 20 — F7 80 — — 20 3000 F8 8013 7 — 3000 F9 80 13 7 — 1000 F10 80 13 7 — 2000 F11 80 13 7 — 1500 F1280 13 7 —  3300^(b) F13 80 13 7 —  3300^(c) F14 80 13 7 — 2500^(a)Concentrations for fuel in percentage, concentration for additive inppm, additive A1 1000 unless indicated ^(b)Additive A3 ^(c)Additive A2

Fuel blends were tested using procedures similar to the one outlined inTitle 13 California Code of Regulations Section 2882 “AromaticHydrocarbon Content of Diesel Fuel.” The actual screening plan is shownin Table 3. For screening, Alternative 3 was the Title 13 protocolselected. For the first two days of testing, duplicate tests with only asingle “prep” were used to quickly move through a large number of fuels.After the first day of testing, the B100 blend with F1 (35 percent) andF2 (65 percent) was selected as the B100 for all subsequent testing. Onthe final two days of testing, the Alternative 3 procedure was followedto screen a 3000 ppm and 2000 ppm additive, respectively. The testresults are reported below in Table 3.

The heavy-duty EPA transient cycle is described by means of percent ofmaximum torque and percent of rated speed for each one-second intervalover a test cycle of 1199 seconds duration. To generate a transientcycle, an engine's full power curve is obtained from an engine speedbelow curb idle speed to maximum no-load engine speed. Data from this“power curve,” or engine map, are used with the specified speed and loadpercentages to form a transient cycle. A graphic presentation of thespeed and torque commands which constitute a transient cycle is given inFIG. 1 for illustration purposes.

In general, a transient test consists of a cold-start transient cycleand a hot-start transient cycle. The same engine command cycle is usedin both cases. For the cold-start, the diesel engine was operated over a“prep” cycle, and then allowed to stand overnight in an ambient soak ata temperature between 68° F. and 86° F. The cold-start transient cyclebegins when the engine is cranked for cold start-up. Upon completion ofthe cold-start transient cycle, the engine is stopped and allowed tostand for 20 minutes. After this hot-soak period, a hot-start cyclebegins with engine cranking. In order to determine how well the enginefollows the transient command cycle, engine performance was compared toengine command, and several statistics were computed. These computedstatistics must be within tolerances specified in the CFR. In additionto statistical parameters, the cycle work actually produced should bebetween 5 percent above and 15 percent below the work requested by thecommand cycle. Emissions measurements included total hydrocarbon (THC),carbon monoxide (CO), oxides of nitrogen (NO), carbon dioxide (CO₂), andtotal particulate matter (PM).

TABLE 3 Step Description 1 Install engine. Perform emission instrumentcalibrations as required. Calibrate torquemeter and check signalconditioning systems. Validate CVS gaseous and particulate samplingsystems using propane recovery techniques 2 Change oil and filters.Operate engine for 5 hours with CARB equivalent fuel to break-in theoil, Check engine condition using in-house, low sulfur emissions typefuel, and note fault codes if any. Bring engine oil level to “full”. 3Perform fuel change procedure to operate on Fuel R (F4). Change filter,purge fuel supply, etc. 4 Warm up engine, and operate at rated speed andload, then check performance. 5 Conduct transient “full-throttle” torquemap from low- to high-idle. Compute and store resulting transientcommand cycle. 6 Run a 20-minute practice or conditioning transientcycle, and adjust dynamometer controls to meet statistical limits fortransient cycle operation. 7 Soak the engine for 20-minutes. Run threehot-start transient tests with a 20-minute soak between each. For eachindividual hot-start test, determine THC, CO, NO_(x), CO₂, and PM. 8Change fuel to F5. Repeat Steps 6 and 7. Soak the engine for 20-minutes. Run two hot- start transient tests with a 20-minute soakbetween each. For each individual hot-start test, determine THC, CO,NO_(x), CO₂, and PM. 9 Change fuel to F6. Repeat Steps 6 and 7. Soak theengine for 20- minutes. Run two hot- start transient tests with a20-minute soak between each. For each individual hot-start test,determine THC, CO, NO_(x), CO₂, and PM. 10 Change fuel to F7. RepeatSteps 6 and 7. Soak the engine for 20- minutes. Run two hot- starttransient tests with a 20-minute soak between each. For each individualhot-start test, determine THC, CO, NO_(x), CO₂, and PM. 11 Change fuelto F8. Repeat Steps 6 and 7. Soak the engine for 20- minutes. Run twohot- start transient tests with a 20-minute soak between each. For eachindividual hot-start test, determine THC, CO, NO_(x), CO₂, and PM. 12Change fuel to F9. Repeat Steps 6 and 7. Soak the engine for 20-minutes. Run two hot- start transient tests with a 20-minute soakbetween each. For each individual hot-start test, determine THC, CO,NO_(x), CO₂, and PM. 13 Change fuel to F10. Repeat Steps 6 and 7. Soakthe engine for 20- minutes. Run two hot-start transient tests with a20-minute soak between each. For each individual hot-start test,determine THC, CO, NO_(x), CO₂, and PM. 14 Change fuel to F11. RepeatSteps 6 and 7. Soak the engine for 20- minutes. Run two hot- starttransient tests with a 20-minute soak between each. For each individualhot-start test, determine THC, CO, NO_(x), CO₂, and PM. 15 Change fuelto F4. Repeat Steps 6 and 7. Soak the engine for 20- minutes. Run twohot-start transient tests with a 20-minute soak between each. For eachindividual hot-start test, determine THC, CO, NO_(x), CO₂, and PM. 16Change fuel to F8. Repeat Steps 6 and 7 except that the fuel filtersshould be dumped, and the engine should be run for 20 minutes at ratedspeed and load prior to Step 7. Soak the engine for 20-minutes. Run twohot-start transient tests with a 20-minute soak between each. For eachindividual hot-start test, determine THC, CO, NO_(x), CO₂, and PM. 17Change fuel to F13. Repeat Steps 6 and 7 except that the fuel filtersshould be dumped, and the engine should be run for 20 minutes at ratedspeed and load prior to Step 7. Soak the engine for 20-minutes. Run twohot-start transient tests with a 20-minute soak between each. For eachindividual hot-start test, determine THC, CO, NO_(x), CO₂, and PM. 18Change fuel to F12. Repeat Steps 6 and 7 except that the fuel filtersshould be dumped, and the engine should be run for 20 minutes at ratedspeed and load prior to Step 7. Soak the engine for 20-minutes. Run twohot-start transient tests with a 20-minute soak between each. For eachindividual hot-start test, determine THC, CO, NO_(x), CO₂, and PM. 19Change fuel to F5. Repeat Steps 6 and 7 except that the fuel filtersshould be dumped, and the engine should be run for 20 minutes at ratedspeed and load prior to Step 7. Soak the engine for 20-minutes. Run twohot-start transient tests with a 20-minute soak between each. For eachindividual hot-start test, determine THC, CO, NO_(x), CO₂, and PM. 20Change fuel to F14. Repeat Steps 6 and 7 except that the fuel filtersshould be dumped, and the engine should be run for 20 minutes at ratedspeed and load prior to Step 7. Soak the engine for 20-minutes. Run twohot-start transient tests with a 20-minute soak between each. For eachindividual hot-start test, determine THC, CO, NO_(x), CO₂, and PM. 21Change fuel to F4. Repeat Steps 4 through 8. 22 Change fuel to F8.Repeat Steps 4 through 8. 23 Change fuel to F4. Repeat Steps 4 through8. 24 Change fuel to F10. Repeat Steps 4 through 8.

For this screening work, a 1991 DDC Series 60 heavy-duty diesel enginewas mounted in a transient-capable test cell. This engine had an inline,six cylinder configuration rated for 365 hp at 1800 rpm. It wasturbocharged and used a laboratory water-to-air heat exchanger for acharge air intercooler. Table 4 lists the engine specifications andfeatures.

TABLE 4 Engine Parameter Comment Make Detroit Diesel Model Series 60,6067GU60 Engine Displacement and Configuration 12.7 L, I-6 EmissionFamily MDD12.7FZAK Rated Power 365 bhp at 1800 rmp Electronic ControlModule DDEC-II Aspiration Turbocharged

For emission testing, the exhaust was routed to a full flow constantvolume sampler (CVS) that utilized a positive displacement pump (PDP),as illustrated in FIG. 2. Total flow in the tunnel was maintained at anominal flow rate of about 2000 SCFM. Sample zone probes were connectedto the main tunnel. These probes were used to collect samples for totalparticulate (PM) and for the gaseous emissions: NON, THC, CO, and CO₂.The NO_(x) was analyzed using a chemiluminescent (CL) analyzer, the THCused a flame ionization detector (FID), and CO and CO₂ was performedusing separate non-dispersive infrared (NDIR) detectors. Probes forbackground gas measurement were connected downstream of the dilution airfilter pack, but upstream of the mixing section. Backgroundconcentrations were determined for all emissions, and the tunnel THCbackground was also determined before and after each test. This engineproduced emission results less than or equivalent to the standards forthat model year. Table 5 compares the 1991 emission standards, theaverage reference fuel emission results, and the percent of standard forthese tests. The engine did not exceed 110 percent of the applicableemission standards for a 1991 model engine.

TABLE 5 Transient Emission, G/HP-HR Test Number THC CO NO_(x) PM 1991Standard 1.3 15.5 5.0 0.25 Reference Fuel 0.1 2.4 4.5 0.19 % of Standard7 16 90 75

FIG. 3 shows a graphical representation of the torque map data for thescreening tests, and FIGS. 4 and 5 show the torque map data for thetests with 3000 ppm and 2000 ppm of the additive, respectively. Table 6gives all of the emission results for THC, CO, NO_(x), PM, and brakespecific fuel consumption (BSFC) obtained for each of the tests. Thistable groups the tests by fuels and additives rather than in the orderthat the tests were performed. The average, standard deviation, andcoefficient of variation for each set of hot-start transient tests arealso included for each fuel. FIG. 6 shows the NOx emissions versusadditive concentration with trend lines for a possible shift inbaseline.

TABLE 6 FUEL TRANSIENT EMISSIONS, g/hp-hr BSFC, WORK, CODE RUN # CO₂ COTHC NO_(X) PM lb/hp-hr hp-hr F4 1308 531.7 2.5 0.10 4.521 0.177 0.37124.61 1309 531.4 2.5 0.10 4.501 0.194 0.371 24.60 1310 531.2 2.5 0.104.506 0.192 0.371 24.60 Average 531.4 2.5 0.10 4.509 0.187 0.371 24.61Std. Dev. 0.247 0.0 0.00 0.010 0.010 0.000 0.002 F4 1340 529.7 2.5 0.094.475 0.189 0.370 24.60 1341 530.0 2.5 0.09 4.487 0.185 0.370 24.61Average 529.9 2.5 0.09 4.481 0.187 0.370 24.60 Std. Dev. 0.232 0.0 0.000.008 0.003 0.000 0.002 F4 1362 531.8 2.4 0.08 4.553 0.180 0.371 24.491363 532.8 2.4 0.08 4.560 0.180 0.371 24.49 1364 533.4 2.4 0.08 4.5650.184 0.372 24.49 Average 532.7 2.4 0.08 4.559 0.181 0.372 24.49 Std.Dev. 0.808 0.0 0.00 0.006 0.002 0.000 0.003 F4 1370 529.4 2.5 0.09 4.4630.184 0.370 24.69 1371 529.6 2.4 0.09 4.474 0.180 0.370 24.69 1372 530.72.5 0.09 4.483 0.179 0.371 24.69 Average 530.2 2.5 0.09 4.478 0.1800.370 24.69 Std. Dev. 0.759 0.1 0.00 0.006 0.001 0.001 0.001 F5 1312532.0 2.3 0.10 4.601 0.162 0.380 24.57 1213 532.1 2.2 0.10 4.607 0.1540.380 24.59 Average 532.1 2.3 0.10 4.604 0.158 0.380 24.58 Std. Dev.0.086 0.1 0.00 0.004 0.005 0.000 0.011 F5 1355 531.0 2.2 0.08 4.5950.151 0.379 24.55 1356 533.1 2.2 0.08 4.630 0.146 0.381 24.56 Average532.0 2.2 0.08 4.613 0.148 0.380 24.55 Std. Dev. 1.476 0.0 0.00 0.0250.003 0.001 0.01 F6 1315 532.1 2.2 0.09 4.622 0.157 0.380 24.57 1316532.1 2.2 0.09 4.620 0.158 0.380 24.58 Average 532.1 2.2 0.09 4.6210.157 0.380 24.58 Std. Dev. 0.026 0.0 0.00 0.001 0.001 0.000 0.008 F71318 531.3 2.0 0.08 4.420 0.154 0.379 24.61 1319 530.8 2.0 0.08 4.4160.149 0.379 24.60 Average 531.0 2.0 0.08 4.418 0.151 0.379 24.61 Std.Dev. 0.350 0.0 0.00 0.003 0.004 0.000 0.004 F9 1324 526.1 2.2 0.08 4.3900.150 0.376 24.63 1325 527.6 2.2 0.08 4.403 0.149 0.377 24.63 Average526.8 2.2 0.08 4.397 0.149 0.376 24.63 Std. Dev. 1.080 0.0 0.00 0.0090.000 0.001 0.00 F11 1330 529.4 2.1 0.08 4.419 0.151 0.378 24.60 1331529.0 2.0 0.08 4.419 0.146 0.378 24.60 Average 529.2 2.1 0.08 4.4190.148 0.378 24.60 Std. Dev. 0.291 0.1 0.00 0.000 0.004 0.000 0.004 F101327 529.2 2.0 0.08 4.405 0.150 0.378 24.60 1328 529.5 2.1 0.08 4.4010.144 0.378 24.60 Average 529.3 2.1 0.08 4.403 0.147 0.378 24.60 Std.Dev. 0.206 0.1 0.00 0.002 0.004 0.000 0.004 F10 1374 533.2 2.1 0.074.449 0.142 0.381 24.68 1375 533.9 2.0 0.07 4.459 0.147 0.381 24.69 1376533.7 2.1 0.07 4.459 0.149 0.381 24.70 Average 533.6 2.1 0.07 4.4550.146 0.381 24.69 Std. Dev. 0.362 0.1 0.00 0.006 0.004 0.000 0.012 F141358 534.7 2.2 0.07 4.483 0.148 0.382 24.53 1359 534.5 2.1 0.07 4.4850.146 0.382 24.55 Average 534.6 2.1 0.07 4.484 0.147 0.382 24.54 Std.Dev. 0.104 0.0 0.00 0.001 0.001 0.000 0.012 F8 1321 528.7 2.0 0.08 4.3560.143 0.377 24.63 1322 529.9 2.0 0.07 4.337 0.143 0.375 24.64 Average529.3 2.0 0.08 4.347 0.143 0.376 24.64 Std. Dev. 0.865 0.0 0.00 0.0130.000 0.001 0.009 F8 1346 528.7 2.0 0.08 4.386 0.142 0.378 24.57 1347529.9 2.0 0.07 4.402 0.143 0.378 24.56 Average 529.3 2.0 0.08 4.3940.142 0.378 24.56 Std. Dev. 0.865 0.0 0.00 0.012 0.001 0.001 0.009 F81366 535.1 2.1 0.07 4.473 0.148 0.382 24.46 1367 534.8 2.0 0.07 4.4800.147 0.382 24.47 1368 534.8 2.1 0.07 4.472 0.149 0.382 24.48 Average534.9 2.1 0.07 4.475 0.148 0.382 24.47 Std. Dev. 0.147 0.1 0.00 0.0040.001 0.000 0.006 F13 1349 531.7 2.0 0.07 4.409 0.150 0.380 24.54 A21350 532.5 2.0 0.07 4.415 0.152 0.380 24.55 Average 532.1 2.0 0.07 4.4120.151 0.380 24.54 Std. Dev. 0.539 0.0 0.00 0.004 0.002 0.000 0.01 F121352 528.0 2.1 0.07 4.389 0.152 0.377 24.58 A2 1353 529.2 2.1 0.07 4.4110.147 0.378 24.59 Average 528.6 2.1 0.07 4.400 0.149 0.378 24.59 Std.Dev. 0.0805 0.0 0.00 0.016 0.004 0.001 0.01

Two different biodiesels were used. F3 was blended at a concentration of20 percent biodiesel in the base fuel, F4 to make F6. The other B20 (20percent biodiesel and 80 percent diesel) blend was a combination of F1at a concentration of 35 percent and F2 at a concentration of 65percent. See Table 2. The blend of these two biodiesels was then mixedwith the base fuel to make a second B20 blend (F5). FIG. 7 compares theemission results for both biodiesels when blended at a concentration of20 percent biodiesel. F5 produced slightly less NO_(x) than the singlecomponent biodiesel blend.

The two B20 blends were then mixed with the additive (A1) at aconcentration of 3000 ppm. F8 was the B20 blend with a combination of F1at a concentration of 35 percent and F2 at a concentration of 65percent, and F7 was the B20 blend with F6 (See Table 2). FIG. 8 comparesthe emission results for the two B20 blends with the additive at 3000ppm. F8 produced slightly less NO_(x) than the single componentbiodiesel blend.

Two additional additives were blended with F8 at a concentration of 3300ppm. The two additives were A2 and A3. The fuel codes were F13 and F12,respectively. FIG. 9 compares the emission results for these twoadditive blends.

Tables 7 and 8 show the statistical approach for comparing the emissionresults with additive A7 at 3000 ppm and 2000 ppm, respectively. Withthis approach, the average emissions from the three (3) individual testswith the candidate fuel, Fuel C (Xc), were compared to the averageemission results for three (3) individual tests with the reference fuel,Fuel R (XR), by using the one-sided t distribution. The average term forthe reference fuel for each emission was adjusted by the tolerance, (1percent of the average for NOx and 2 percent of the average for CO andPM) and by a value that included: tolerance, δ and pooled standarddeviation, S_(p).

Square root of two divided by the number of tests, n, for both referenceplus candidate (in this case, n=14, to represent the potential result ifthe entire seven day test protocol was performed) One-sided upperpercentage point oft distribution with a=0.15 and 2n−2 degrees offreedom. The equation for this comparison isX_(C)<X_(R)+δ−(S_(p)×√2/η×t(a, 2n−2)). See CCR Title 13, Chapter5—Standards for Motor Vehicle Fuels, Article 3—Specifications forAlternative Motor Vehicle Fuels. Values presented in Table 7 and 8 werebased on a spreadsheet calculation. If the average for the candidatefuel is less than the adjusted average for the reference fuel, then thecandidate fuel is comparable or better than the reference fuel.

TABLE 7 Statistical Criteria NO_(x) CO PM Number of Test 14 14 14Points, n^(a) C Average, X_(c) ^(b) 4.475 2.081 0.148 R Average, X_(R)^(b) 4.559 2.364 0.181 Tolerance Level, δ^(c) 0.046 0.047 0.004 Pooledstd. Dev., Sp^(b) 0.005 0.048 0.002 Sqrt of 2/n 0.378 0.378 0.378Student's t, t^(d) 1.058 1.058 1.058 Adjusted R Average, 4.603 2.3920.184 Adj. X_(R) ^(b,e) Is X_(c) < Adj. X_(R) Yes Yes Yes PercentReduction, r 2.8 13.0 19.7 ^(a)For alternative 4, n = number of tests(plus reference candidate) ^(b)Units are in g/bhp-hr ^(c)Tolerance levelis 1 percent for NO_(x) and 2 percent for CO and PM One-sided student'st for 2n−2 degrees of freedom and significance level of 0.15 Adj. X_(R)= X_(R) + δ − (S_(p) × √{square root over (2)}/η × t(a, 2n−2)) wheret(a, 2n−2) is 1.055

TABLE 8 Statistical Criteria NO_(x) CO PM Number of Test 14 14 14Points, n^(a) C Average, X_(c) ^(b) 4.455 2.090 0.146 R Average, X_(R)^(b) 4.473 2.475 0.181 Tolerance Level, δ^(c) 0.045 0.050 0.004 Pooledstd. Dev., Sp^(b) 0.008 0.072 0.003 Sqrt of 2/n 0.378 0.378 0.378Student's t, t^(d) 1.058 1.058 1.058 Adjusted R Average, 4.515 2.4960.183 Adj. X_(R) ^(b,e) Is X_(c) < Adj. X_(R) Yes Yes Yes PercentReduction, r 1.3 16.3 20.4 ^(a)For alternative 4, n = number of tests(plus reference candidate) ^(b)Units are in g/bhp-hr ^(c)Tolerance levelis 1 percent for NO_(x) and 2 percent for CO and PM One-sided student'st for 2n−2 degrees of freedom and significance level of 0.15 Adj. X_(R)= X_(R) + δ − (S_(p) × √{square root over (2)}/η × t(a, 2n−2)) wheret(a, 2n−2) is 1.055

F5 was used in a further blend as follows.

120 gallons of F4 base fuel used as the untreated diesel blend stockwere transferred into a clean tote. 30 gallons of F5 and 1703 ml of2-ethylhexyl nitrate fuel additive were added. The fuel was blended forone hour with an air-actuated stirrer, and a sample was taken foranalysis. The fuel properties for the candidate fuel blend are shown inTable 9 together with the properties for base fuel F4. For the fattyacid methyl ester (FAME), the analysis showed that the concentration was19.8 percent by volume. The resulting treated candidate fuel, Fuel C,was then identified as F15.

TABLE 9 F4 Base Fuel Value F15 Candidate Fuel Value Sulfur, ppm 0.9Sulfur, ppm 1.56 Nitrogen, ppm 1.7 Nitrogen, ppm 284.4 Cetane number49.3 Cetane number 59.1 API Gravity 35.8 API Gravity 34.4 Flash Point, °F. 197.5 (91.8) Flash Point 190 (88) (° C.) Viscosity @ 40° C., 3.00Viscosity @ 40° C., 3.14 cSt cSt IBP, ° F. 400 IBP, ° F. 409 10%, ° F.451 10%, ° F. 461 50%, ° F. 490 50%, ° F. 521 90%, ° F. 592 90%, ° F.629 EP, F. 636 EP, F. 644 FAME Content, % — FAME Content, % 19.8

Fuel tests were performed utilizing Alternative 3 outlined above and inoutlined in Title 13 California Code of Regulations Section 2882. Table10 provides the testing protocol that was used. F4 is referred to as“Fuel R” for Reference Fuel and F15 is referred to as “Fuel C” forCandidate Fuel.

TABLE 10 Step Description 1 Install engine. Perform emission instrumentcalibrations as required. Calibrate torquemeter and check signalconditioning systems. Validate CVS gaseous and particulate samplingsystems using propane recovery techniques 2 Check engine condition usingin-house, low sulfur emissions type fuel, and note fault codes if any.Bring engine oil level to “full”. 3 Perform fuel change procedure tooperate on Fuel R (F4). Change filter, purge fuel supply, etc. 4 Warm upengine, and operate at rated speed and load, then check performance. 5Conduct transient “full-throttle” torque map from low- to high-idle.Compute and store resulting transient command cycle. 6 Load dummy samplemedia, and run a 20-minute practice or conditioning transient cycles,and adjust dynamometer controls to meet statistical limits for transientcycle operation 7 Soak the engine for 20-minutes. Run three hot-starttransient tests with a 20-minute soak between each. For each individualhot-start test, determine THC, CO, NO_(x), CO₂, and PM. 8 Perform fuelchange, and repeat Steps 3 through 7 with Fuel C. 9 On Day 2 of testing,repeat Steps 4 through 9 starting with Fuel C and ending with Fuel R. 10On Day 3 of testing, repeat Steps 4 through 9 starting with Fuel R andending with Fuel C. 11 On Day 4 of testing, repeat Steps 4 through 9starting with Fuel C and ending with Fuel R 12 On Day 5 of testing,repeat Steps 4 through 9 starting with Fuel R and ending with Fuel C. 13On Day 6 of testing, repeat Steps 4 through 9 starting with Fuel C andending with Fuel R. 14 On Day 7 of testing, repeat Steps 4 through 9starting with Fuel R and ending with Fuel C. 15 Summarize data andprepare the final report.

Table 11 gives the emission results for HC, CO, NO_(x), PM, and brakespecific fuel consumption (BSFC) obtained for each of the tests. Theaverage for each set of triplicate hot start transient tests was alsoincluded for each fuel.

TABLE 11 TEST TRANSIENT EMISSIONS, g/hp-hr BSFC, WORK, NUMBER CO₂ THC CONO_(X) PM lb/hp-hr hp-hr R1 538.0 2.437 0.077 4.621 0.183 0.378 24.39 R2538.1 2.432 0.081 4.620 0.182 0.378 24.39 R3 539.1 2.530 0.083 4.6200.182 0.378 24.39 Average 538.4 2.466 0.080 4.621 0.183 0.378 24.39 C4539.6 2.122 0.075 4.540 0.147 0.388 24.35 C5 540.4 2.026 0.071 4.5380.146 0.389 24.35 C6 540.3 2.026 0.071 4.542 0.148 0.389 24.36 Average540.1 2.058 0.072 4.540 0.147 0.388 24.35 C7 539.0 2.121 0.070 4.5130.148 0.388 24.39 C8 539.9 2.061 0.066 4.512 0.149 0.388 24.38 C9 539.51.997 0.070 4.523 0.149 0.388 24.38 Average 539.5 2.060 0.069 4.5160.149 0.388 24.38 R10 539.7 2.485 0.085 4.597 0.188 0.379 24.39 R11539.9 2.551 0.086 4.600 0.188 0.379 24.38 R12 539.6 2.469 0.087 4.6150.190 0.379 24.40 Average 539.7 2.502 0.086 4.604 0.189 0.379 24.39 R13537.1 2.543 0.078 4.567 0.183 0.377 24.41 R14 538.0 2.462 0.079 4.5680.185 0.378 24.43 R15 538.1 2.438 0.081 4.584 0.184 0.378 24.42 Average537.7 2.481 0.079 4.573 0.184 0.377 24.42 C16 539.2 2.035 0.068 4.5130.146 0.388 24.36 C17 538.9 2.059 0.071 4.514 0.149 0.388 24.35 C18539.9 2.143 0.073 4.526 0.148 0.388 24.35 Average 539.3 2.079 0.0714.518 0.148 0.388 24.35 C19 532.1 2.045 0.064 4.432 0.129 0.383 24.40C20 532.9 2.026 0.067 4.436 0.144 0.383 24.40 C21 532.9 2.029 0.0694.447 0.148 0.383 24.38 Average 532.7 2.033 0.067 4.438 0.141 0.38324.39 R22 534.6 2.558 0.082 4.553 0.182 0.375 24.38 R23 535.3 2.5580.085 4.561 0.190 0.376 24.38 R24 535.7 2.496 0.087 4.564 0.186 0.37624.39 Average 535.2 2.537 0.085 4.559 0.186 0.376 24.38 R25 528.2 2.4850.077 4.482 0.187 0.371 24.48 R26 529.0 2.564 0.080 4.493 0.187 0.37124.48 R27 529.3 2.475 0.082 4.502 0.190 0.372 24.48 Average 528.8 2.5080.080 4.492 0.188 0.371 24.48 C28 532.9 2.155 0.066 4.437 0.151 0.38324.37 C29 532.9 2.088 0.066 4.440 0.152 0.383 24.37 C30 534.0 2.2070.068 4.447 0.151 0.384 24.37 Average 533.3 2.150 0.067 4.441 0.1510.384 24.37

Table 12 shows the statistical approach for comparing the emissionresults. With this approach, the average for each of the triplicateresults from the 21 individual tests with the candidate fuel, Fuel C(Xc), were compared to the average for each of the triplicate resultsfor 21 individual tests with the average reference fuel, Fuel R (XR), byusing the calculations describe above withX_(C)<X_(R)+δ−(S_(p)×√2/η×t(a, 2n−2)).

TABLE 12 Statistical Criteria HC CO NO_(x) PM Number of Test 14 14 14 14Points, n^(a) C Average, X_(c) ^(b) 0.082 2.509 4.540 0.187 R Average,X_(R) ^(b) 0.068 2.080 4.463 0.147 Tolerance Level, δ^(c) 0.002 0.0500.045 0.004 Pooled std. Dev., Sp^(b) 0.003 0.033 0.065 0.003 Sqrt of 2/n26 26 26 26 Student's t, t^(d) 1.058 1.058 1.058 1.058 Adjusted RAverage, 0.082 2.546 4.560 0.189 Adj. X_(R) ^(b,e) Is X_(c) < Adj. X_(R)Yes Yes Yes Yes Percent Reduction, r 17.5 18.3 2.1 22.1 ^(a)Foralternative 1, n = number of tests (plus reference candidate) ^(b)Unitsare in g/bhp-hr ^(c)Tolerance level is 1 percent for NO_(x) and 2percent for HC, CO, and PM ^(d)df = 2(n−1) One-sided student's t for2n−2 degrees of freedom and significance level of 0.15 Adj. X_(R) =X_(R) + δ − (S_(p) × √{square root over (2)}/η × t(a, 2n−2)) where t(a,2n−2) is 1.055

As shown, the candidate fuel was found to decrease the NO_(x) emissionsby 2.1 percent when compared to the reference fuel. The PM emissionswere decreased by about 22 percent and average HC and CO were lower(17.5 and 18.3 percent lower, respectively).

The contents of all references (including literature references, issuedpatents, published patent applications, and co-pending patentapplications) cited throughout this application are hereby expresslyincorporated herein in their entireties by reference. Unless otherwisedefined, all technical and scientific terms used herein are accorded themeaning commonly known to one with ordinary skill in the art.

1. A biodiesel fuel mixture composition comprising a) 12-15 wt. % of afirst biodiesel fuel; b) 6-8 wt. % of a second biodiesel fuel; c) 79-81wt. % of a base petroleum diesel fuel; and d) from 1000 to 3500 ppm2-ethylhexyl nitrate, wherein the biodiesel fuel mixture has a cetanenumber of 45 to
 70. 2. The biodiesel fuel mixture of claim 1 comprisinga) 13 wt. % of a first biodiesel fuel; b) 7 wt. % of a second biodieselfuel; and c) 80 wt. % of a base petroleum diesel fuel.
 3. The biodieselfuel mixture of claim 1, wherein the biodiesel fuel mixture has a cetanenumber of 45 to
 65. 4-9. (canceled)
 10. The biodiesel fuel mixture ofclaim 1, wherein the mixture comprises 25% or less of aromatics byvolume. 11-15. (canceled)
 16. The biodiesel fuel mixture of claim 1,wherein the mixture comprises less than 7% polycyclic aromatics byweight.
 17. (canceled)
 18. (canceled)
 19. The biodiesel fuel mixture ofclaim 1, wherein the weight ratio of total aromatics to polycyclicaromatics in the mixture is 5:1.
 20. (canceled)
 21. (canceled)
 22. Thebiodiesel fuel mixture of claim 1, wherein the weight ratio of totalaromatics to polycyclic aromatics in the mixture is 2:1.
 23. Thebiodiesel fuel mixture of claim 1, wherein the sulfur content is lessthan 15 ppm. 24-26. (canceled)
 27. The biodiesel fuel mixture of claim1, wherein the nitrogen content is from 0 ppm to about 800 ppm. 28-30.(canceled)
 31. The biodiesel fuel mixture of claim 1, wherein the fattyacid methyl ester content is 19 to 21%.
 32. The biodiesel fuel mixtureof claim 1, wherein the viscosity at 40° C. is 1.9 to 4.1 centistokes.33. The biodiesel fuel mixture of claim 1, wherein the 2-ethylhexylnitrate is present in an amount of 1000, 1500, 2000, 2500, 3000, or 3300ppm.
 34. The biodiesel fuel mixture of claim 1, wherein the 2-ethylhexylnitrate is present in an amount of 3300 ppm or 3000 ppm.
 35. (canceled)36. (canceled)
 37. (canceled)
 38. The biodiesel fuel mixture of claim 1,wherein the mixture has no negative impact on NO_(x) emissions. 39.(canceled)
 40. The biodiesel fuel mixture of claim 1, wherein themixture decreases NO_(x) emissions of an engine by 2 to 7%. 41.(canceled)
 42. (canceled)
 43. The biodiesel fuel mixture of claim 1,wherein the mixture decreases total particular matter emissions of anengine by 20 to 25%.
 44. The biodiesel fuel mixture of claim 1, whereinthe mixture decreases CO emissions of an engine by 15 to 25%.
 45. Thebiodiesel fuel mixture of claim 1, wherein the mixture decreases totalhydrocarbon emissions of an engine by 15 to 25%. 46-50. (canceled)